In verifying the theory of pattern recognition, benchmark like importance has been attached to researches in face recognition, such that many techniques have so far been developed. The application, presupposed in these researches, is mostly in need of high degree of accuracy under static environment, such as authorization in a security system and retrieval of individuals from a large-scale database.
Recently, a robot apparatus for entertainment, formed to an outer shape like that of an animal, such as a dog, has been presented to the market. This robot apparatus is responsive to the information from outside, such as information of the surrounding environment, or to the internal state, such as the feeling state, to cause autonomous action of eyes or limbs, to manifest the behavior like that of an animal.
As this robot apparatus has made its debut, there has been developed a human interfacing technique for causing the robot apparatus to respond within a preset time more or less accurately even under an environment which is changed dynamically. As typical of this technique, face identification by the robot apparatus has been a desideratum. For example, if face identification is used, the robot apparatus is able to identify the user (keeper) from many to enhance its entertainment properties.
In an application for face identification, loaded on the robot apparatus, the following problems:    (1) that, since the robot apparatus itself is moved, changes in the environment or its diversity must be tolerated;    (2) since the position relationships between the human being and the robot apparatus are changed, the human being must be in the field of view of the robot apparatus during interactions;    (3) an image usable for discriminating the human being must be selected from numerous scenes and verified comprehensively; and    (4) that reply must be made in certain preset time.